1. Field of the Invention
A common place substitution for the traditional wooden doors in residential and commercial buildings are synthetic doors. One type of synthetic doors is formed with resin sheets reinforced with fiber glass (in the art referred to as skins) attached to opposite sides of a rectangular frame with resulting cavity between the skins filled with a plastic foam. Doors so constructed can include wood graining on their outer surfaces of the skins, and also raised paneling formed (molded) in the skins, which gives these doors the appearance of natural wood fabricated products.
Molded skins for making such doors of the type described are disclosed in U.S. Pat. No. 3,950,894 issued to DiMaio and in U.S. Pat. No. 4,550,540 issued to Thorn. These skins are typically formed using mixtures, having by weight 12% to 15% polyester resin, 5% to 15% polystyrene, 40% to 50% calcium carbonate and 15% to 25% chopped fiberglass. Such mixtures are layered in a compression molding machine and subjected to pressures from 600 to 1,500 psi for a cure cycle from 60 to 200 seconds to form rigid skins. The mixture described is one of those known xe2x80x98sheet molding compoundsxe2x80x99 [SMCs]. A general description of the sheet molding process is found in an article entitled, xe2x80x9cCompression Moldingxe2x80x9d by N. D. Simons in Modern Plastics Encyclopedia, Vol. 54 No. 10A (1977-78).
Skins formed from SMC processes for doors can have thicknesses of from about 0.13 mm (0.05 inches) to about 52 mm (0.20 inches), depending on the door application in which they are used.
As previously noted such skins are affixed to opposite sides of a rectangular frame and the core (cavity) enclosed by the frame and skins is filled with a plastic foam to complete the door. A rigid urethane foam having a density of 0.8 pounds per cubic foot to 3.5 pounds per cubic foot is suitable for the core of such doors.
Prior art conventional molded doors of the type described can be generally classified, according to height, into two types: one is the standard molded door with a height of about 200 cm (or about 6 feet 8 inches), and the custom molded door with a height of about 250 cm (or about 8 feet), both doors are made in conventional widths, with the width of 94 cm (or about 3 feet) being the most common. Special molded doors may be 10 or 12 feet high.
In the past these prior art doors had glass inserts [lights] that covered less than 30% of the door""s exterior surface, see e.g., U.S. Pat. No. 4,720,951 issued to Thorn. Currently the market place demands doors with large glass inserts or lights which can comprise more than 60% of the doors exterior surface. Due to building codes these large lights must be double glazed (double pane) and in some cases made of safety glass. As a result the insert may weigh in the range of 16.5 to 37.5 kilograms (44 to 100 lbs) and the skins in such doors are not capable of satisfactorily supporting this weight without innovations in the door structure for supporting the insert. This is particularly true in the taller, custom molded door structures and is especially true in the special molded doors described above.
This invention relates to improved molded doors composed of skins disposed on a door frame of stiles and rails which have a large central glass insert, by providing interior reinforcing means disposed adjacent to an insert frame structure formed in and joining the opposing skins, which cooperatively strengthen the door and enables a transfer of the weight of the insert to the door components without deformation or bending of the perimeter frame door due to the weight of the glass insert. Moreover the invention prevents flexing of the door components which otherwise might dislodge the large glass insert.
Thus it is an object to provide a molded door which is constructed in a manner to support large glass inserts while still taking advantage of the features available when using the SMC skins, such as wood graining, resistance to insect infestation, etc.
Another object of the invention is to arrange reinforcing (anti-bending means) in the interior of a custom molded door with large glass insert to strengthen it without creating an interference with the subsequent installation of the door hardware, e.g. latching mechanisms and hinges.
A further object of the invention is to incorporate internal structures in molded door with a large glass insert, particularly in the custom molded doors, to avoid deformation, flexing, twisting and the like resulting from the weight of the glass insert when the door is placed in service.
The further feature of the invention is to install reinforced anti-bending means inside a custom molded door with glass insert and against each internal wall of glass frame used for installing glass insert of molded door skin with opening to directly support the full weight of glass insert and strengthen the structural strength using anti-deformation and anti-bending elements.
An improved molded door having provisions for glass insert comprising at least 50% of said door""s exterior surface includes a quadrilateral frame formed of a top rail, a bottom rail, a right stile and a left stile joined together, two sheets of molded door skins, each skin having a large central opening with an inwardly directed flange extending normal to its planer surface and around its respective opening, which flanges interlock when assembled on frame and form secondary frame for receiving a glass insert, means operable to join the skins to the quadrilateral frame, means operable to join the integral flanges of the skins in an interlocked relationship around their respective openings thereby forming an interlocked secondary frame for receiving a glass insert, a secondary left stile located between the joined flanges and the left stile with this stile joined to the skins and a secondary right stile located between the joined flanges and the right stile with this stile joined to said skins.